The use of polymerizable dental restorative materials capable of being cured by short-term (usually one minute or less) exposure to high-intensity light has become popular in recent years. Such a material allows a dentist all of the time needed to mold and shape the material in a prepared cavity or on a prepaved surface. Curing is commenced only when the dentist is satisfied with the results of the prior steps. The light may be of any suitable wavelength although preferably light in the visible spectrum is used, thereby avoiding the risks of exposure to light of shorter wavelengths (i.e., ultraviolet light.) After a few seconds of exposure to the high-intensity light, transmitted from the light source to a hand-held wand by means of a fiber-optic cable, the restoration is ready for final trimming and finishing.
Despite the advantages of such a system, it has been discovered that problems and disadvantages do exist. A conventional wand contains the distal end of the fiber-optic cable, the wand having a rigid tubular tip that supports the end of the cable and permits a dentist to direct the light to the area of restoration. Sufficiency of light exposure is critical for proper curing; consequently, conventional systems commonly include an electronic or mechanical timer which the dentist pre-sets according to the manufacturer's instructions. (The duration of recommended exposure ordinarily varies with the shade and brand of the restorative material selected.) However, should the dentist hold the tip of the wand too far away from the area of restoration, inadequate curing may result. Should the tip be too close, the lighted area may not be large enough to cure the entire restoration, leaving marginal areas incompletely cured, or the tip may inadvertently contact the uncured restorative material, marring the prior work and possibly causing the restorative material to cling to, and subsequently harden upon, the tip of the wand.
Another problem in the use of conventional systems concerns the discomfort and temporary visual impairment that may result should the patient (or anyone else) look directly at the tip of the wand while it is illuminated. Even the dentist may be affected by direct or reflected light as he (she) looks directly at the restoration area during light-curing. In an effort to reduce such problems, some manufacturers provide filter caps that may be fitted over the tips of the wands to reduce the intensity of the light and thereby reduce eye discomfort and "after-image" effects; however, such filter caps also have the disadvantage of reducing the illuminating efficiency of such a system and increasing the light exposure time required for polymerization of the restorative materials.
A main object of this invention therefore lies in providing an improved apparatus which overcomes or at least greatly reduces the problems associated with conventional systems for photo-curing polymerizable dental restorative materials. Specifically, it is an object to provide a system in which means are provided for accurately controlling the distance between the tip of a wand and the area of restoration during a light-curing step, for intensifying the light directed to the restorative area during such a step, and for protecting the dentist against exposure to reflected light that might otherwise cause eye discomfort and after-image effects. It is a further object to provide such improvements while at the same time reducing the possibilities of direct contact between the tip of the wand and uncured material at the site of restoration that might mar the restoration and impair the usefulness of the instrument. In addition, the means for achieving such results also tends to protect the patient from visual exposure to light from the tip of the wand that might otherwise result in discomfort and temporary visual aberrations.
Briefly, the apparatus includes a light source, a light-directing wand adapted to be hand-held by the user (a dentist or dental assistant), a fiber-optic cable for transmitting light from the source to the wand, and a frusto-conical shield detachably connected to the tip of the wand. The shield has a collar portion extending from its reduced end, the collar being adapted to receive the tip portion of the wand. The shield is preferably opaque, or at least of low light transmissibility, and may be formed of relatively stiff polymeric material. The opening at the shield's enlarged end has a diameter falling generally within the range of 0.35 to 0.85 inches, the preferred range being approximately 0.40 to 0.65 inches. The angle of slope of the frusto-conical shield may fall within the general range of 15.degree. to 35.degree. (measured from the longitudinal axis of the shield), with a range of 20.degree. to 25.degree. being preferred.
A holder, adapted to be mounted near the dental tray or at any other convenient location, may be used to support the shielded wand when it is not in use but may nevertheless be illuminated, so that the risks a dentist or patient might be dazzled by the high-intensity light will be significantly reduced prior to or immediately following a light-curing operation. Efficiency is promoted by providing a light box having a plurality of sockets illuminated by a single light source, so that the same source is used to illuminate not only the light wand but also one or more other handpieces and/or diagnostic instruments.
Other features, objects, and advantages of the invention will become apparent from the specification and drawings.